Electron-tube construction



Jan. 11, 1927.

M. B. FORRESTER ELECTRON TUBE CONSTRUCTION Filed April 11.

II I llll INVENTOR. -/%'/0 jdzzresfsm, BY g 9 ATTORNEY Patented Jan. 11, 1927.

i ranger MELVYN .B. FORRESTER, OF PHILADELPHIA, EENNSYLVAKIA,

TIMMONS, INCL, OF SYLVANIA.

assrsnon r0 3. s.

PHILADELPHIA, PENNSYLVAIUA, A CORPORATION OF PENN- ELECTBON-TUBE CON STBUCT ION.

Application filed April 11, 1925.

My invention relates broadly to electron tubes and more particularly to a construction of electron tube in which the elements are protected against displacement, short circuit and ultimate destruction.

One of the objects of my invention is to provide a mounting for the heated cathode within an electron tube formed from means which extend from one of the electrodes within the tube for providing a substantial assembly of electrodes which maybe inexpensively manufactured on a quantity production basis.

Another object of my invention is to provide an electron tube construction in which the elements are rigidly mounted upon rod n'ienibers which extend longitudinally upw: "d within the tube with insulation means extending between the upper extremities thereof and forming a brid 'e from which the other electrodes may be srspended.

Still another object of my invention is to provide a contruction of electron tube having a more positive mechani al relation between the elements thereof, the tube being designed for manufacture in an economical manner, either as a two electrode rectifying device or a three electrode electron tube.

Still another object of my invention is to provide an insulated bridge member within an electron tube extending across one of the electrodes and supported thereby for providing a support for other electrodes and in some instances a resilient support for a heated cathode for preventing the displacement of the position of the cathode under conditions of temperature changes.

Other and further objects of my invention will be understood from the specification hereinafter following by reference to the accompanying drawings, wherein:

Figure 1 is a side view, partially broken away, showing the construction of a rectifier tube made in accordance with my invention;

Fig. 2 is'a view of the electron tube illustrated in Fig. 1, looking in the direction of the length of the anode within the tube; Fig. 3 is a perspective view of the resilient member which I provide between the insulated bridge and the cathode for maintaining the filament in spaced relation at all times with reference to other electrodes 'ithin the tube; Fig. l is a view illustrating the mounting of three electrodes withtended upwardly vmember of insulation Serial No. 22,340.

in an electron tube and the suspension thereof irom the insulated bridge; and Fig. 5 IS an enlarged detail view illustrating the method of supporting the insulated bridge from one of the members extending from the plate electrode.

My invention finds particular application in a two electrode electron tube arranged to function as a rectifier although the construction is equally applicable in three electrode electron tubes. The manufacture of tubes on a quantity production scale is greatly facilitated by the arrangement of electrodes which I utilize the same supports I have devised.

which position the plate electrode within the tube for maintaining the cathode in a central position and stretched taut at all times under conditions of variat-ion'in temperature. In my construction detrimental elfects arising from shocks and jars or the tendency of the cathode to become shunted with other electrodes within the tube is eliminated. The electrical characteristics of the tube are thus maintained constant and the uniformity of tubes is insured over a large number of tubes in a production program. In my construction, rods which form the support for one of the electrodes are exand are connected at their extremities by a cross-rod which may be spot we'lded to the upwardly extending rods. The cross-rod extends through a cylindrical material, from which member other electrodes within the tube are supported. Between the extremity of the cathode and the'cylindrical member of insulation material I may interpose a spiral spring having connecting means on opposite ends thereof whereby the position of the cathode may be maintained in a central plane within the tube structure and the oathode prevented from accidentally contacting and contacts 3, 4 and 5 projecting from the lower surface of the base. A central insulated portion 6 extends upwardly within the tube forming a support for rods 7 and 8 which are bent substantially at right angles and extend upwardly as shown at 11 and 12 forming means for supporting the plate electrode formed by sections 9 and 10. The rods 7 and 8 extend upwardly above the por tious 11 and 12 to positions indicated at 14: and 15 and across the extremities of which is connected a rod member 16. The rod member 16 may be flattened at its ends as represented at 18 in Fig. 5, which flattened faces are contacted with flattened faces 19 on the extremities of the upwardly extending rod portions 1% and 15 and spot-welded or otherwise joined thereto. A cylindrical member of insulation material 17 extends throughout the length of rod member 16 between the upwardly extending rod portions lt and 15 forming an insulated bridge across the top of the tube electrodes from which other electrodes for the tube may be supported. A spiral spring member 20 is provided which has a hook portion 22 on one extremity and a spiral portion 21 on its opposite extremity, which spiral portion extends on an axis substantially perpendicular to the axis of the spiral spring member 20. The spiral portion 21 envelops the member of insulation material 17, while the hook portion 22 supports the upper extremity of the cathode 23 and tends to constantly stretch the cathode taut under conditions of change in siZe in accordance with changes in temperature. The lower extremities of the cathode 23 are supported by members 24 and 25. The plate members 9 and 10 are further supported by the member 26 extending from the insulated support 6. In the case of a three electrode tube, as represented in Fig. 4, rod members 28 depend from the member of insulation material 17, the rod members 28 being hooked over the member of insulation material 17 as represented at 27 and forming a support for the grid electrode 29. By this arrangement the member of insulation material 17, supported from the plate electrode, serves as a support and spacing member for the grid and filamentelectrodes within the tube. All tendency of the cathode to sag against another or the electrodes within the tube is avoided by means of the resilient spring device 20. V The construction illustrated has proved to be practical in quantity production manufacture and efficient in its electrical operation.

, While I have described my invention in a certain particular embodiment, I desire that it be understood that modifications may be made and that I intend no limitations upon the invention other than those imposed by the scope of the appended claim.

Vv hat 1 claim and desire to secure by Letters Patent of the United States is as follows:

In an electron tube the combination of an anode and a cathode, a pair of rods supporting said anode and extending vertically upwardly within said tube, said rods having their upper extremities flattened, a rod disposedsubstantially at right angles to said pair of rods and having its opposite ends flattened for interconnecting the upper flattened portions on the extremities of said aforementioned rods, an insulated tube enclosing said second mentioned rod and means depending from said insulated tube and forming a support for said cathode.

In testimony whereof I attix my signature.

MELVYN B. FORRESTER. 

